This invention relates generally to adjustable end arm effectors usable with industrial robots; and more specifically, to the set-up of such an adjustable end arm effector.
In general, industrial robots include an articulated arm which is controlled by programming. The articulated arm typically ends in a support which is used to attach an end arm thereto which holds a workpiece interfacing tool. As used herein, the end arm, including any base used to attach the end arm to the articulated arm, and the tool are referred to, collectively, as an xe2x80x9cend arm effector.xe2x80x9d
End arm effectors can include adjustable elements. For example, a workpiece interfacing tool may be attached to an end arm in utilizing an adjustment mechanism such that the rotation, angle and/or location of the tool with respect to an arm may be modified. Less commonly, the rotation, angle and/or length of a particular end arm may be adjustable relative to its base or attachment point to the articulated arm.
Examples of adjustable end arm effectors are disclosed in the following U.S. Pat. Nos.: 5,383,738 entitled xe2x80x9cBall Jointed Linksxe2x80x9d which issued to Herbermann on Jan. 24, 1995; 5,135,276 entitled xe2x80x9cTransfer Boomxe2x80x9d which issued to Blatt et al. on Aug. 4, 1992; and U.S. Pat. No. 5,071,309 entitled xe2x80x9cMounting Arrangement for a Multi-Function Armxe2x80x9d which issued to Herbermann on Dec. 10, 1991 all hereby incorporated herein by reference.
Utilizing adjustable end arm effectors can offer significant advantages. For example, the need to fabricate an end arm effector for each specific application is eliminated. Instead the components from an adjustable end arm effector can simply be readjusted for use in another application. This can save considerable time and money in comparison to the traditional fixed end arm effector manufacturing process.
Appropriate adjustments must be made during a set-up process to utilize adjustable end arm effectors. This may be done, for example, initially or after an industrial robot crash which impacts the adjustments. For example, coordinated transfer mechanisms which have miss-sequenced have been known to crash end arm effectors. In one known set-up process, a master workpiece is located on the load or unload fixture. The industrial robot is located in the work position with respect to the workpiece. Then, appropriate adjustments are made to the various end arm effectors that interact with the workpiece. One disadvantage of this set-up process is the requirement that when multiple adjustable arm end arm effectors are utilized, all of the arms are adjusted at one time while the robot remains in one position. Another disadvantage is the amount of space that can be required and the difficulty storing and managing the master workpiece part; particularly when the workpieces are large sheet metal components. Another disadvantage associated with this known set-up process is that the parts are often located with respect to the master workpiece based on visual inspection, rather than utilizing tactile feedback which can provide more accurate positioning.
In accordance with the present invention an adjustable end arm effector alignment system is provided. The system includes an arm having a working end and an alignment support in a known location relative to the arm. Also included is an adjustable end arm effector attached to one of the working end of the arm and the alignment support. In one aspect, the adjustable end arm effector includes at least two alignment members. The system additionally includes at least one cooperating alignment member attached to the other of the working end of the arm and the alignment support. The at least one cooperating alignment member is adapted to cooperate with the at least two alignment members. In another aspect, the cooperating alignment member includes a feature other than the workpiece interfacing feature of the workpiece interfacing tool that is adapted to cooperate with the alignment member. In yet another aspect of the present invention, a cooperating alignment member is included that has a cooperating mechanical alignment feature in a known location relative to the adjustable end arm effector. The mechanical alignment feature and the cooperating mechanical alignment features are adapted to provide mechanically cooperating engagement which, when cooperatively engaged, operates to accurately locate the first alignment member in a specific aligned position when the adjustable end arm effector is appropriately adjusted with respect thereto. An additional aspect includes a control system that is operable to move the working end of the arm into one or more alignment positions where one of the at least two alignment members cooperates with the at least one cooperating alignment member to identify when the adjustable end arm effector is appropriately adjusted with respect thereto.